Esbjerg will be competing in the new season in the NordicBet League outfit, as they bid to return to the Danish top-flight.
Wolfe, 21, who made his first-team debut from the bench in the Reds' fateful final home game of the 2019-20 season against Nottingham Forest, had a short loan spell at Notts County last term.
Defender Helliwell, 19, was the Reds' 2017-18 Academy player of the year and made his first team debut in coming on as a late substitute against Bradford City in a 2-1 victory in the Checkatrade Trophy at Oakwell in November, 2018.
Also 19, Winfield, is also to operate at left-back or in midfield.
Canada-born striker Simpson joined Barnsley in October, 2020 after impressing on trial. He signed a one-year contract extension earlier this month.